Self-sustaining on-site production of electricity and/or steam for use in the in situ processing of oil shale and/or oil sands

ABSTRACT

Oil shale and/or oil sands are utilized to generate electricity and/or steam at the site of the oil shale/sands deposit in an in situ process for recovering oil from the deposit. Bulk shale/sands material is removed from the deposit and combusted to generate thermal energy. The thermal energy is utilized to heat water to generate steam. The steam can be used directly in the in situ process or utilized to drive a steam turbine power generator located in close proximity to the deposit to generate electricity. The electricity generated on-site may be utilized to drive an in situ conversion process that recovers oil from the oil shale/sands deposit. Also, the exit steam generated by the on-site turbine generator can be used on-site to drive the in-situ conversion process.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/819,601, filed on Jul. 10, 2006, by William B. Hendershot and titled“Self-Sustaining On-Site Production of Electricity for Use in the InSitu processing of Oil Shale and/or Oil Sands.” U.S. ProvisionalApplication No. 60/819,601, filed Jul. 10, 2006, is hereby incorporatedby reference herein in its entirety.

This patent application is a Continuation-In-Part of co-pendingapplication Ser. No. 11/429,907, filed on May 8, 2006, by William B.Hendershot, titled “Self-Sustaining On-Site Production of ElectricityUtilizing Oil Shale and/or Oil Sands Deposits”, which is aContinuation-In-Part of application Ser. No. 11/093,690, filed on Mar.30, 2005, by William B. Hendershot, titled “Self-Sustaining On-SiteProduction of Electricity Utilizing Oil Shale”, which (1) is aContinuation-In-Part of application Ser. No. 10/618,948, filed on Jul.14, 2003, by William B. Hendershot, titled “On-site Production ofElectricity Utilizing Oil Shale”, now abandoned, and (2) claims thebenefit of Provisional Patent Application No. 60/560,498, filed on Apr.7, 2004, by William B. Hendershot, titled “On-site Production ofElectricity Utilizing Oil Shale.” Application Ser. No. 11/429,907,application Ser. No. 11/093,690, application Ser. No. 10/618,948, andProvisional Patent Application No. 60/560,498 are each herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to energy production from oil shale and/oroil sands deposits and, in particular, to an efficient technique forproducing electricity and/or steam in close proximity to the site of anoil shale/sands deposit and utilizing a portion of the on-site-generatedelectricity and/or the on-site produced steam, or both, to facilitatethe in situ retorting of oil shale/sands. The use and recycling ofresources and heat energy developed at the site of the oil shale/sandsdeposit further contributes to the self-sustaining aspect of theinvention.

2. Discussion of the Related Art

As discussed in a 2005 report authored by Bartis et al. for the RANDCorporation and titled “Oil Shale Development in the United States”, itis well known that there are very large oil shale deposits in a numberof locations throughout the world. These oil shale deposits hold some ofthe largest oil reserves in the world. The reason that only a very smallamount of this oil is currently extracted from these deposits for use inproducing energy is the prohibitively high cost, in terms of botheconomics and environmental impact, associated with extracting the oilfrom the oil shale. The RAND Corporation report provides a detaileddiscussion of the prospects and policy issues related to oil shaledevelopment in the United States. Similar issues apply to the vast oilsands deposits that exist in North America, primarily in Canada.

A number of methods for recovering oil from oil shale have beenproposed. The technology disclosed in U.S. Pat. No. 4,265,307, issued onMay 5, 1981, and titled “Shale Oil Recovery”, is an example.

As discussed in '307 patent, oil shale is composed of inorganic matter(rock) and organic matter called “kerogen.” When oil shale is heated atelevated temperatures on the order of 600° F. to 900° F. in the absenceof significant oxygen, kerogen is destructively distilled to form ahydrocarbon gas, shale oil and carbon. Shale oil at elevated temperatureis in the vapor phase, while the carbon is in the form of coke.Continued heating of shale oil causes decomposition to form more gas andmore coke.

As further discussed in the '307 patent, beginning in the 1920's, thefirst proposals for recovering oil from shale were referred to as “truein situ combustion.” As the name suggests, these methods involved the insitu, or in the ground, combustion of the oil shale. Heat necessary forrecovering the hydrocarbons was to be supplied by in situ combustion,combustion being accomplished along a combustion front that moved fromone end of the oil shale deposit to the other end of the deposit duringthe recovery operation.

The true in situ combustion technique was first tried in the 1950's andwas attempted a number of times in the 1950's and the 1960's. Incarrying out this process, small fissures were introduced into the oilshale deposit by hydrofrac techniques prior to combustion in order toexpedite the passage of vaporous shale oil out of the bed.Unfortunately, the true in situ combustion technique was not successful.

In the early 1970's, a modification of the true in situ combustiontechnique was first tried. This technique, referred to as the “modifiedin situ combustion technique”, differs from the true in situ combustiontechnique in that, prior to in situ combustion, partial mining aroundthe oil shale deposit is accomplished to provide a greater flow path forthe escape of the shale oil. Also prior to combustion, the shale oildeposit is broken up or fragmentized (referred as “rubblized”) intochunks or pieces. This is usually accomplished by means of explosives.However, the modified in situ combustion technique also proved to beineffective in larger shale oil deposits, where yields were only around30% of theoretical.

U.S. Pat. No. 4,472,935, issued to Acheson et al. on Sep. 25, 1984,discloses an example of a modified in situ oil shale combustiontechnique. In accordance with the method disclosed in the '935 patent, asubsurface oil shale formation is penetrated by both a production welland an injection well. While the shale itself remains in the ground, thefluids produced by the production well are delivered through a line intoan above ground separator in which low heating value (LHV) gases in theproduced fluids are separated from the liquids in the produced fluids.The liquids are discharged from the bottom of the separator into a linefor off-site delivery and the LHV gases are discharged from the top ofthe separator into a feed line. The LHV gases are preheated, mixed withair and then burned in a catalytic combustion chamber. The combustionproducts discharged from the combustion chamber are then expanded in aturbine to generate electricity.

In addition to in situ combustion, other techniques have been proposedfor the recovery of shale oil from oil shale by the in situ heating ofthe oil shale. These techniques include the utilization of electricalenergy for heating the oil shale and the utilization of radio frequencyenergy rather than combustion to furnish the necessary heat.

Oil sands deposits are typically exploited using either the modified insitu combustion technique described above or an open pit mining process.

The modified in situ combustion technique involves the process describedin the above-cited Acheson et al. '935 patent, wherein both a productionwell and an injection well are formed in the oil sands deposit. Theinjection well is used to drive heat into the deposit, forcing the“bitumen” hydrocarbons in the deposit into the production well forextraction.

In the more commonly used open pit mining technique, thebitumen-containing oil sands are removed from the deposit using scoopingand conveyor systems. The extracted bulk oil sands are then transportedto a processing facility using either huge dump trucks or a water-slurrytransport system. The processing plant uses water to separate thebitumen form the sand. The bitumen is then processed to removeimpurities and then further processed in a coking tower system thatultimately provides a “sweet crude” hydrocarbon product. The open pitmining technique is clearly environmentally insensitive and energyinefficient.

The above-cited RAND report describes an in situ retorting processenvisaged in the early 1980s by researchers at Shell Oil, which theynamed the In-Situ Conversion Process. Referring to FIG. 1, according tothe In-Situ Conversion Process, a volume of shale is heated by electricheaters that are placed in vertical holes drilled through the entirethickness (more than a thousand feet) of a section of oil shale. Toobtain even heating over a reasonable period of time, fifteen totwenty-five heating holes are drilled per acre. After heating for two tothree years, the targeted volume of the deposit reaches a temperature ofbetween 650 and 700° F. This very slow heating to a relatively lowtemperature, compared with the plus-900° F. temperature common in theabove-described surface retorting processes, is sufficient to cause thechemical and physical changes required to release the oil from theshale.

FIG. 2 shows the major process steps associated with Shell in situconversion process. As part of the site preparation, the Shell processuses ground-freezing technology to establish an underground barrieraround the perimeter of the extraction zone, creating a “freeze wall” bycirculating a refrigerated fluid through a series of wells drilledaround the extraction zone. In addition to preventing groundwater fromentering the extraction zone, the freeze wall keeps hydrocarbons andother products generated by retorting from leaving the project perimeterduring ground heating, product extraction and post extraction groundcooling. Of course, both the site preparation and the extraction phasesinvolve the construction of power plants and power transmission lines tosupply the electricity both to the refrigeration systems and to theunderground heaters.

While, as indicated above, numerous attempts have been made toeffectively capture oil from oil shale and/or oil sands deposits overthe years, no technique has yet been developed that provides acommercially-viable and environmentally-sensitive production leveltechnique for recovering energy from these huge deposits.

SUMMARY OF THE INVENTION

The present invention provides systems and methods for generatingelectricity and/or steam in close proximity to oil shale and/or oilsands deposits and, preferably, with optimum utilization of localsupplemental energy resources and recycled energy and materials. Theelectricity and/or steam generated on-site is then utilized to drive anin situ conversion process of the type described above.

In accordance with the general concepts of the invention, an electricalpower generating facility is located in close proximity to an oil shaledeposit or an oil sands deposit (hereinafter referred to inclusively asan “oil shale/sands deposit”). Oil shale/sands removed from the depositis provided to an on-site, above ground burn container in bulk form.Supplemental heat energy, preferably obtained from on-site fuelresources and/or recycled materials, may be provided to supplement thecombustion process in the on-site burn container. The heat energygenerated by the combustion process in the burn container is utilized toheat water to generate steam. The steam drives a steam turbine powergenerator that is part of the on-site power generating facility. Thesteam turbine generates electricity at least a portion of which isutilized at the site to drive an in situ recovery process, for example,a process similar to the Shell in situ conversion process describedabove, that recovers oil from the oil shale/sands deposit.Alternatively, the steam may be used directly in the in situ conversionprocess.

Calculations made utilizing widely available data show that, if one acreof an oil shale/sands deposit contains 1,500,000 barrels of oil (as inthe case of the Green River Formation discussed in the above-cited RANDreport), a recovery technique in accordance with the present invention,that is, generating electricity and/or steam on site using oilshale/sands from the deposit and then utilizing the on site generatedelectricity and/or steam to drive an in situ conversion process, wouldproduce approximately a net 547,000 barrels of oil per acre. At a priceof $50 per barrel, the value of oil product produced from a single acreof the deposit would be $27,350,000, or $17.5 billion per square mile.It is reliably estimated that the Green River Formation and its mainbasins cover about 16,000 square miles in Utah, Wyoming and Colorado.

In an embodiment of the present invention, the oil shale/sands removedfrom the deposit to feed the above ground burn container is taken fromthe perimeter of the targeted in situ process recovery zone, therebydefining a trench around the in situ recovery zone. Creation of aperimeter trench around the in situ recovery zone not only provides theenergy resource needed to drive the on-site generation of electricityfor use in the in situ recovery process, but also, in the case of theShell in situ conversion process, minimizes the “freeze wall” energyrequirement.

These and additional features and advantages of the present inventionwill be more fully appreciated upon consideration of the followingdetailed description of the invention and the accompanying drawings thatset forth a number of illustrative embodiments in which the concepts ofthe invention are utilized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a known in situ conversion process for recovering oilfrom an oil shale deposit.

FIG. 2 is flow chart showing the general steps involved in the FIG. 1 insitu conversion process.

FIG. 3 is a flow chart illustrating a method of recovering oil from oilshale/sands in accordance with the concepts of the present invention.

FIG. 4 is a block diagram illustrating an embodiment of a system andmethod for generating electricity from oil shale/sands deposits inaccordance with the concepts of the present invention.

FIG. 5 is a block diagram illustrating a more detailed embodiment of asystem and method for generating electricity from oil shale/sandsdeposits in accordance with the concepts of the present invention.

FIG. 6 is a schematic drawing illustrating a dual parabolic solarreflector utilizable in generating electricity from oil shale/sandsdeposits in accordance with the concepts of the present invention.

FIG. 7 is a schematic drawing illustrating an alternate embodiment of adual parabolic solar reflector utilizable in generating electricity fromoil shale/sands deposits in accordance with the concepts of the presentinvention.

FIG. 8 is a block diagram illustrating an alternate embodiment of asystem and method for generating electricity and/or hydrocarbon productsfrom oil shale/sands deposits in accordance with the concepts of thepresent invention.

FIGS. 9A-9D illustrate utilization of spent hot oil shale/oil sands topreheat bulk oil shale/oil sands input to a recovery vessel inaccordance with the concepts of the present invention.

FIGS. 10A and 10B show the utilization of a sealing wall in a trenchformed around a targeted in situ oil recovery zone, in accordance withthe concepts of the present invention.

FIGS. 11A and 11B show two embodiments of a piping scheme for utilizingsteam generated on the site of an oil shale/sands deposit in the in siturecovery of oil from the deposit

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a technique that utilizes oil shaleand/or oil sands to generate electricity and/or steam in close proximityto the site of the oil shale/sands deposit for use in the in siturecovery of oil from the oil shale/sands deposit, thereby making the oilrecovery process self-sustaining.

FIG. 3 shows the steps of a self-sustaining method of recovering oilfrom an oil shale/sands deposit. An electrical generating system 10generates electricity 12 on site utilizing hydrocarbon productsrecovered from the oil shale/sands deposit 14. The electricity 12generated on site is utilized to recover oil from the deposit utilizingan in situ recovery technique; for example, as shown in FIG. 3, theelectricity generated on site can be used to drive both therefrigeration function 16 and the underground heating function 18 of theShell in situ conversion process.

FIG. 4 shows one embodiment of a system 100 for generating electricityon-site utilizing oil shale and/or oil sands in accordance with thepresent invention.

The system 100 includes an electrical power generating facility 102 thatis located in close proximity to an oil shale/sands deposit 104. It isdesirable to locate the electrical generating facility 102 as close tothe deposit 104 as possible, the location of the facility 102 beingdependant upon local conditions, including the size of the deposit 104itself. The distance from the deposit 104 to the generating facilityshould, preferably, be less than 20 miles.

The power generating facility 102 includes a steam turbine powergenerator 106 of the conventional type utilizable for generatingelectricity. As indicated in FIG. 4, in accordance with this embodimentof the invention, oil shale and/or oil sands 108 in bulk form (i.e.,greater than about 1.5 in. diameter in the case of oil shale) is removedfrom the deposit 104 and provided to an on-site, above groundconventional burn container 110, such as, for example, a fluidized bedreactor. Those skilled in the art will appreciate that, in the case ofoil shale, the bulk oil shale 108 can be “rubblized” or “pulverized”(i.e., crushed to pieces less than about 1.5 in. diameter) prior to itsintroduction into the above ground burn container 110. Supplemental fuel112, which can be, for example, propane, but which preferably is fuelobtained from a renewable source local to the deposit 104 (e.g., ethanolobtained from corn grown in proximity to the deposit 104) may beprovided to the burn container 110 such that hydrocarbons contained inthe bulk oil shale/sands 108 are combusted in the burn container 110 togenerate thermal energy. The thermal energy generated by the burncontainer 110 is utilized to heat water 114, preferably provided by alocal source, to generate steam 116. The steam 116 drives the steamturbine power generator 106 to generate electricity 118. At least aportion of the on site generated electricity 118 can be utilized todrive a conventional in situ recovery process, as discussed above. Anyexcess electricity 118 not required for the in situ process can bedistributed as desired utilizing a conventional electricity distributionsystem or grid or, as discussed in greater detail below, used on-site tomake the power generation process more self-sustaining.

FIG. 5 shows a more detailed embodiment of the FIG. 4 system 100. Asshown in FIG. 5, recoverable by-products 121 resulting from thecombustion of bulk oil shale/sands 108 in the above ground burncontainer 110 include fine potash, including potassium carbonate andpotassium hydroxide. It is well known that potassium carbonate is usedas a granular powder in making glass, enamel and soaps; potassiumhydroxide is a caustic white solid used as bleach and in making soap,common dyes and alkaline batteries (lye). Thus, the commercial need forpotassium carbonate and potassium hydroxide could justify the cost ofdisposing of this by-product of the burn container 110. Furthermore, thespent rock and/or sands 122 resulting from the combustion of the oilshale/sands 108 in the burn container 110 can be returned to theoriginal deposit 104 to minimize the environmental impact of “mining”the bulk oil shale/sands 108.

As in the FIG. 4 system, thermal energy generated in the burn container110 heats water 114, preferably from a local source, to produce steam116 that drives a steam turbine generator 106. Steam turbine generator106 generates electricity 118 that is utilized in an in situ recoveryprocess, exported for off-site use, or used in the electricitygeneration process.

As further shown in FIG. 5, exhaust steam heat 124 from the steamturbine power generator 106, which can be at a temperature of 350-400°C., and/or exhaust heat 126 from the burn container 110, can be recycledand used to provide preheat energy 128 to the bulk oil shale/sands 108as it comes from the deposit 104 to the burn container 110. Thecombination of the recycled preheat energy 128 and the supplemental fuel112 can result in a temperature that will cause the bulk oil shale/sands108 entering the burn container 110 to be easily crumpled to a finepowder, thereby facilitating removal of the shale oil and otherhydrocarbons contained in the bulk material 108 as it is heated in theburn container 110. As mentioned above, if the heat provided from thesesupplemental and/or recycled sources is insufficient, some amount ofrefining, e.g., rubblizing/pulverizing of bulk oil shale, may berequired prior to introduction of the bulk material 108 into the burncontainer 110 to facilitate more efficient recovery of thermal energyfrom the shale oil hydrocarbons contained in the bulk material 108.Crushing can be powered utilizing the excess steam 124 and/or theelectricity 118 generated on-site.

Alternatively, some form of radiant energy, e.g. microwaves, could beused to preheat the bulk material 108, thereby dissolving the kerogencontained therein. As in the FIG. 4 embodiment, the supplemental fuel112 provided to the burn container 110 can be propane or other locallyobtained waste material such as for example, wood, sawdust, trash ormanure that can be utilized to generate heat in the burn container 110or to preheat the bulk material 108.

As further shown in FIG. 5, the water 114 utilized to generate steam 116for driving the steam turbine power generator 106 can be preheatedutilizing a parabolic solar reflector system 130 (described in greaterdetail below).

The steam exhaust heat 124 from the steam turbine power generator 106,which, as stated above, typically will be around 350-400° C., can alsobe utilized to assist in the fermentation of locally grown corn toproduce ethanol as a supplemental fuel 112 for the burn container 110.Alternatively, the ethanol could be used in dissolving kerogen containedin the bulk material 108, thereby improving the efficiency of thecombustion process in the burn container 110.

FIG. 6 shows an embodiment of a parabolic solar reflector system 130that can be used in the FIG. 5 system. The center of the parabolicreflector system 130 near the axis, which is flatter and moreperpendicular to the sun's rays, is used to generate electrical energyutilizing solar panels 131 mounted on the parabolic reflector surface133. The outer edge reflects solar rays to a black sphere 135 located ata focal point to heat the water ultimately provided as the steam sourceto the turbine generator 106.

As stated above, exhaust steam 124 from the steam turbine powergenerator 106 can be used to preheat the bulk material 108 or can bereused as input to the steam tank.

FIG. 7 provides a more detailed illustration of a preferred embodimentof a parabolic solar reflector system 130. In the FIG. 7 embodiment, theparabolic reflector 130 includes a first parabolic reflecting surface132 having a first curvature that conforms, as illustrated, to theequation Y²=20x. The parabolic reflector 130 also includes a secondparabolic reflecting surface 134 that conforms to a second equation,shown in FIG. 3 as Y²=10x. Both the first parabolic reflecting surface132 and the second parabolic reflecting surface 134 have the same focalpoint. A black sphere 136 located at the common focal point of the firstparabolic reflecting surface 132 and the second parabolic reflectingsurface 134 receives water 114 from the input source and providespreheated water to the burn container 110 for generation of steam 116.As further shown in FIG. 7, the first parabolic reflecting surface 132of the parabolic reflector 130 has solar collectors 138 mounted thereonfor generating electricity from the solar energy captured by the solarcollectors. The system 130 can include solar tracking equipment thatcontinuously adjusts the position of the reflecting surfaces 132, 134 inresponse to changes in the position of the sun to obtain maximum captureof solar energy.

FIG. 8 illustrates an alternate embodiment of a system 500 for theself-sustaining generation of electricity using oil shale and/or oilsands removed from an oil shale/sands deposit 502. As in theabove-described embodiments of the invention, oil shale and/or oil sandsin bulk form 504 are removed from the deposit 502 and provided to anon-site, above ground burn container 506, such as, for example, afluidized bed reactor. As discussed above, supplemental fuel 508 may beprovided to the burn container 506 such that hydrocarbons contained inthe bulk material 504 are combusted to generate thermal energy withinthe burn container 506. Thermal energy generated in the burn container506 is utilized to heat water 510, preferably from a local source 511,to generate steam 512. The steam 512 drives a steam turbine powergenerator 514 that generates electricity 516 for off-site distribution518; as discussed below, a portion of the electricity generated on-sitecan be used in the energy recovery process.

As further shown in FIG. 8, bulk material 504 a may also be removed fromthe deposit 502 and provided to a preheat system 520. Preheated bulkmaterial 522 from the preheat system 520 is provided to a surfacerecovery vessel 524 in which heat is used to drive hydrocarbons from thepreheated bulk oil shale/sands material 522 in liquid form 525 and/or invapor form 526, as is done in conventional surface oil shale retortingprocesses; in contrast to the conventional surface retorting technique,the heat required for the surface recovery vessel 524, preferably, allderives from the deposit 502. The hydrocarbon vapors 524 driven from thebulk material 522 are cooled in a condenser 528 to provide liquid oiland/or hydrocarbon product 530 that can be distributed off-site togetherwith the liquid product 525; a portion of the product 525, 530 can usedas supplemental fuel in various other stages of the recovery process.Condenser 528 may be cooled using water, which, in this case, wouldrequire additional use of water from the local source 511. However, asshown on FIG. 8, preferably, the condenser 528 is electrically driven bypower 518 generated by the on-site generator 514, thereby reducing theburden on the local water resource 511.

Also, although not shown in the FIG. 8 block diagram, a portion(preferably less than 20%) of the oil/hydrocarbon output 525, 530 of thesurface recovery vessel 524 can be recycled to assist combustion in anyor all of the burn container 506, the preheat system 533 and the surfacerecovery vessel 524 itself. The combustion efficiency in each of thesesystems can be optimized by varying the percentage of the various fuelsused in the system. Also, if one or more of these systems is notfunctioning properly at any given time, the generation of electricityand oil/hydrocarbon product can continue by simply increasing theutilization of the other systems. For example, the bum container 506 canact as a buffer to supply larger amount of electricity while the surfacerecovery vessel 524 is being loaded/unloaded between cycles.

As further shown in FIG. 8, a portion of the electrical 516 energygenerated by the steam turbine power generator 514 can be utilized toheat the surface recovery vessel 524. Furthermore, supplemental heat forthe recovery vessel 524 can be obtained by the combustion of bulk oilshale/sands material 504 b taken from the deposit 502.

As additionally shown in FIG. 8, spent bulk material 532 that resultsfrom the heating process in the surface recovery vessel 524, and thatcan have a temperature in the range of 450° C., can be provided to apreheat system 534 in which the water 510 is preheated prior tointroduction to the burn container 506, thereby reducing the fuel burdenon the burn container 506 and increasing the overall efficiency of thesystem 500.

FIGS. 9A-9D combine to show an embodiment of a preheating system 520(FIG. 8) that can be utilized to preheat the bulk material 504 a that isprovided to the surface recovery vessel 524. As shown in the side viewof FIG. 9A and its corresponding cross section in FIG. 9B, the preheatsystem 520 includes a lower conveyer belt 536 that runs in a direction(shown by the lower arrow) that carries spent material from the recoveryvessel 524 and a second, upper conveyer belt 538 that runs in anopposite direction to deliver bulk material 504 a from the deposit 502to the recovery vessel 524. The dual-conveyer belt system 536, 538 issurrounded by insulation 540 on all four sides, as illustrated in FIGS.9A and 9B, in order to minimize heat loss and, thus, obtain maximumbenefit of the recycled heat provided by the spent material 532 from therecovery vessel 524. Thus, oil sand/shale material 502 a to be input tothe recovery vessel 524 can be preheated by spent hot shale/sandmaterial 532 that is removed from the recovery vessel 524 and passes onthe lower conveyer 536 in an opposite direction. The volume of the spentshale/sands material 532 and preheated oil shale/sands 522 on theconveyor belts can equal a full load in the recovery vessel 524;however, up to 25% of the spent shale/sands 532 at 450° C. could remainin the recovery vessel 524 for use in preheating the next cycle of bulkmaterial introduced to the vessel 524. FIGS. 9C and 9D provide detailsof the transfer of spent shale/sand 532 and pre-heated oil shale/sand522 to and from the recovery vessel 524, respectively.

It should be understood that, although FIG. 8 shows the utilization ofonly one steam turbine generator 514 in the system 500, multiple steamgenerators could be utilized with, for example, some of the generatorsproviding power for use in an in situ recovery process and some of thegenerators providing power to an off site grid. Using a number ofsmaller generators (e.g., one steam generator per four square miles ofthe overall oil shale/sands deposit 502) would, thus, provide greaterflexibility to the system 500. The use of small portable steamgenerators would enable these generators to be moved from site to siteon the deposit 502 as the different areas of the deposit 502 aredeveloped, thereby reducing the overall cost of energy production.

As discussed above, the Shell in situ conversion process requires thecreation of a “freeze zone” around the perimeter of the targeted depositrecovery zone. Creation of the “freeze zone” requires a large amount ofelectricity to drive the refrigeration system needed to sustain thefreeze zone for up to three years. In accordance with an embodiment ofthe present invention, shown in FIG. 10A, the energy requirement forsuch a “freeze zone” can be significantly reduced, if not eliminated, byremoving the oil shale/sands needed for the on-site generation ofelectricity, as discussed in detail above, from the perimeter of the insitu recovery zone, thereby creating a trench 600 around the in siturecovery zone 602. A combination of a trench 10 and a reduced-sizerefrigeration system utilizing holes 604 drilled in the bottom of thetrench 600, as shown in FIG. 10B, could also be utilized.

It might be possible for heated liquid oil to seep through the wall 606of the trench 600. Therefore, as shown in FIGS. 10A and 10B, reusablemetal plates 608 that fit together to form an oil seal could be used sothat oil from the in situ recovery zone 602 does not pass into thetrench 600. As further shown in FIGS. 10A and 10B, a catch trough 610can be placed between the inside of the plates 608 and the oilshale/sands deposit 602 to capture “seepage” oil, which can be recoveredfor use off- site, or on site as discussed above.

Also, suitable thermal insulation 612 can be applied on the outside ofthe metal plates 608 to greatly reduce heat loss from the in siturecovery zone 602. The insulated perimeter must have a lower outwardheat flow from the heated in situ zone than having the same heated zonesurrounded by the conventional “freeze zone” utilized in the Shellprocess.

The oil shale/sands that remains in the zone between the fully liquefiedin situ recovery zone and the sealing plates around the perimeter of therecovery zone can be used after the oil is recovered form the in situzone to generate electricity on site as discussed above.

Several potential uses of the exhaust steam heat from the steam turbinepower generator 106 are discussed above in conjunction with the FIG. 5block diagram. As stated above, this exhaust steam 124 is typically at atemperature of 350-400° C. (assuming a 1000° C. steam inputtemperature). This exhaust steam 124 could be also be used to heat thein situ recovery zone in the above-described in situ conversion process.It is believed that the amount of exhaust steam available from the steamturbine power generator would be sufficient to provide 100% of thethermal energy required to heat the in situ zone in accordance with thetypical operating parameters for this process; alternatively, a portionof the exhaust steam could be utilized to supplement the electricityused to drive the heating of the in situ zone, thereby reducing theoverall electrical power requirement for this purpose. Water resultingfrom the utilization of the exhaust steam for this purpose could berecovered from the in situ zone and recycled for use in steam generationas discussed above.

The steam exiting the steam turbine generator can be held at 400° C. orhigher by controlling the input temperature of the steam to the turbinegenerator. As shown in FIG. 11A, the exit steam can then be circulatedthrough the oil shale/sand deposit in pipes to cause the oil in thedeposit to liquefy. In this embodiment of the invention, the steam doesnot mix with the oil. Rather, the steam remains inside the pipes, whichpreferably are inserted in the drilled holes in the in situ hot zone, asdiscussed above. These same holes may be used to insert electricalheating rods, as discussed above, to supplement the steam heating ifneeded.

Since the heat energy in the exit steam from the turbine generatorcontains about 50% of the input energy, as compared to 36% in theon-site generated electrical energy, using the exit steam is moreefficient than using on-site generated electricity to heat the oilshale/sands in the in situ hot zone.

The further cooled steam, after utilization for heating the oilshale/sands in the in situ conversion process, can be recycled for usein the boiler.

EXAMPLE

Compare oil/dollars out of one square mile of an oil shale/sands depositusing on-site generated steam versus on-site generated electricity inthe in situ conversion process in accordance with the invention asdescribed above.

Electricity

At 36% efficiency, it takes 446,400 MegW per square mile, or 1,240,00 MWheat into the boiler to drive the in situ process using on-sitegenerated electricity.

Steam

At 50% efficiency, it takes 892,800 MegW heat into the boiler to drivethe in situ process using exit steam from the on-site turbine generator.

That is, the steam alternative is 28% more efficient than theelectricity alternative and the generator still produces 446,400 MegWelectricity that can be used on or off site. This 446,400 MegW ofelectricity is equivalent to 274,000,000 barrels of oil from thedeposit. Thus, in the recycled steam embodiment of the invention, theoverall output of 1 square mile of the oil shale/sands deposit is theequivalent of 1,234,000,000 barrels of oil which, at $50 per barrel, hasa value of about $62 Billion.

Those skilled in the art will appreciate that the utilization of theexhaust steam is a very efficient utilization of a by-product of theon-site generation of electricity and, because it is generated on-site,can be utilized at substantially full efficiency because it does notneed to be piped any great distance for use. However, of the exit steamfrom the turbine generator is used more than about 5 miles from theturbine generator, the heat from the stem will dissipate greatly,thereby reducing oil recovery efficiency.

As an alternative, use of the steam from the burn container 110 (seeFIGS. 4 and 5, for example) directly for heating the hot zone in an insitu recovery process within a 5 mile radius of the burn container 110(i.e. the surrounding 80 square miles) with the steam turbine generator106 turned off, the output steam from the burn container 110 would notneed to be over 1000° C. as in the case when the turbine generator 106is being powered by the steam from the burn container 110. Using thesteam directly from the burn container 110 would greatly reduce theamount of burned oil shale/sands used to heat the burn container 110 byabout 36%. When the turbine generator 106 is needed to provideelectricity to heat the hot zone area out to about 300 square milesaround the turbine generator 106, the generator 106 is simply turned onand the output temperature of the steam from the burn container 110 isincreased to 1000° C. Those skilled in the art will appreciate that itis not difficult to run electricity up to about 10 miles. Also, anycombination of on-site generated electricity and on-site generated steamcan be used in the in-situ recovery process.

The recovery process described above would require about 50 steamturbine generator systems to recover oil from the Colorado/Utah/Wyomingoil shale deposits described in the above-cited RAND report. After usingone of these systems to fully exploit one region of the deposit, thesystem could be moved and reused at one or more additional sites.

Steam may also be used to pressure the liquid oil generated in thein-situ recovery process toward the exit port. This steam would not coolsubstantially because it would be in contact with hot oil and shale.Additional drill holes might be needed at the outer perimeter of the insitu hot zone for the insertion of steam in these perimeter regions.

It should also be understood that systems of the type described abovecould include the latest available pollution control technology. Forexample, all of the hydrocarbon combustion systems could be fitted withscrubbers to minimize air pollution.

All steps of the processes needed for the on-site generation ofelectricity from oil shale can be facilitated by the electric powergenerated from on-site. For example, the following can be achieved byusing this electricity:

-   -   raw mining of oil shale and/or oil ands    -   removal of raw oil shale/oil sands from the mine    -   crushing oil shale    -   heating crushed oil shale and/or oil sands to the point of        evaporation    -   condensing oil vapor to reclaim the liquid oil    -   pumping the liquid oil to a desired location for cracking

It should be understood that various alternatives to the embodiments ofthe invention described herein might be employed in practicing theinvention. It is intended that the following claims define the scope ofthe invention and that methods and systems within the scope of theseclaims and their equivalents be covered thereby.

1. A self-sustaining method of recovering oil shale/sands deposit, themethod comprising: generating electricity at the site of the oilshale/sands deposit utilizing hydrocarbon products recovered from theoil shale/sands deposit; and utilizing the electricity generated at thesite of the oil shale/sands deposit to drive an in situ conversionprocess for recovering oil from the oil shale/sands deposit. 2.(canceled)
 3. A method as in claim 1, and wherein the electricitygenerated at the site of the oil shale/sands deposit is utilized todrive the underground heating function of the in situ conversionprocess.
 4. A method as in claim 1, and wherein the step of generatingelectricity at the site of the oil shale/sands deposit comprises:locating an electrical power generating facility that includes a steamturbine power generator in close proximity to the oil shale/sandsdeposit; removing oil shale/sands from the oil shale/sands deposit inbulk form; providing the removed oil shale/sands to an above ground burncontainer; providing supplemental fuel to the burn container such thathydrocarbons contained in the oil shale/sands provided to the burncontainer are combusted to generate thermal energy; using the thermalenergy generated by the burn container to heat water to generate steam;providing the steam to the steam turbine power generator such that thesteam turbine power generator generates electricity on the site of theoil shale/sands deposit.
 5. A method as in claim 4, and wherein the oilshale/sands are removed from a perimeter portion of the oil shale/sandsdeposit to define a perimeter trench around an interior portion of theoil shale/sands deposit.
 6. (canceled)
 7. A method as in claim 4, andwherein the oil shale/sands provided to the above ground burn containercomprises rubblized oil shale.
 8. A method as in claim 4, and whereinthe oil shale/sands provided to the above ground burn containercomprises pulverized oil shale.
 9. A method as in claim 4, and furthercomprising: recovering potash generated by combustion of the oilshale/sands hydrocarbons.
 10. A method as in claim 4, and furthercomprising: returning spent oil shale/sands resulting from combustion ofthe oil shale/sands hydrocarbons to the oil shale/sands deposit.
 11. Amethod as in claim 4, and further comprising: preheating the water priorto utilizing the thermal energy generated by the burn container to heatthe water to generate steam.
 12. A method as in claim 11, and furthercomprising: preheating the water utilizing a parabolic solar reflector.13. A method as in claim 12, and further comprising: adjusting theposition of the parabolic reflector to track the position of the sun.14. A method as in claim 11, and further comprising: preheating thewater utilizing a dual parabolic reflector that includes a firstparabolic surface having a focal point and a second parabolic reflectingsurface having the same focal point as the first parabolic reflectingsurface, the water being passed through the common focal point of thefirst and second parabolic reflecting surfaces.
 15. A method as in claim14, and wherein the first parabolic reflecting surface has solarcollectors mounted thereon for generating electricity from solar energycaptured by the solar collectors.
 16. A method as in claim 4, andwherein the supplemental fuel includes propane.
 17. A method as in claim4, and wherein the supplemental fuel is obtained from a source locatedin close proximity to the oil shale/sands deposit.
 18. A method as inclaim 17, and wherein the supplemental fuel comprises ethanol derivedfrom a crop grown in close proximity to the oil shale/sands deposit. 19.A method as in claim 4, and further comprising: utilizing exhaust heatfrom the electrical power generating facility to heat the oilshale/sands provided to the burn container.
 20. A method as in claim 4,and further comprising: utilizing exhaust heat from the electrical powergenerating facility to pre-heat the oil shale/sands prior to itsintroduction to the burn container.
 21. A method as in claim 4, andfurther comprising: providing supplemental fuel to pre-heat the oilshale/sands prior to its introduction to the burn container.
 22. Amethod as in claim 1, and wherein the step of generating electricity atthe site of the oil shale/sands deposit comprises: removing oilshale/sands from the oil shale/sands deposit in bulk form; combustingthe removed bulk oil shale/sands above ground to generate heat energy;utilizing the heat energy at the site of the oil shale/sands deposit togenerate electricity; utilizing at least some of the generatedelectricity in the removing and/or combusting steps. 23.-37. (canceled)38. A system that generates electricity and hydrocarbon products, thesystem comprising: an electrical power generating system that includesan on-site steam turbine power generator located in close proximity toan oil shale/sands deposit: an above ground burn container that combustsoil shale/sands material removed from the oil shale/sands deposit toproduce thermal energy utilized to produce steam that drives the steamturbine power generator to generate electricity; and an on-site in situconversion system that recovers hydrocarbon products from the oilshale/sands deposit utilizing electricity generated by the steam turbinepower generator. 39.-42. (canceled)
 43. A method of recovering oil froman oil shale/sands deposit, the method comprising: removing oilshale/sands material from a perimeter region of a portion of the oilshale/sands deposit to define a perimeter trench around said portion ofthe oil shale/sands deposit; utilizing the oil shale/sands materialremoved from the oil shale/sands deposit to generate electricity at thesite of the oil shale/sands deposit; and utilizing the electricitygenerated at the site of the oil shale/sands deposit in the in siturecovery of oil from said portion of the oil shale/sands deposit.44.-48. (canceled)